Field of the Invention
Embodiments of the invention relate to optical sensors and the integration of optical sensors with application-specific integrated circuit (ASIC) dies for the purpose of high-performance signal processing and package size reduction.
Background
Optical sensors can be used for a variety of applications including, for example, ambient light sensors, IR sensors, gesture, remote control, gaming, heartbeat monitors, blood oxygen monitors, fiber-optic data transfer, and digital cameras. Such applications can be used in diverse fields such as consumer electronics, healthcare, or telecommunications. Optical sensor modules can include an optical sensor die and an associated die, such as one or more amplifiers, analog-to-digital converters, microcontrollers etc. The associated die may be configured to process the output signal from the optical sensor die.
In many cases, the optical sensor die is separately packaged, and the packaged sensor is then provided in electrical communication with an adjacent ASIC. One reason for this is the sensor and ASIC may use different fabrication process technology. Some current packaging schemes for optical sensors include clear mold packages, cavity packages having clear lids or an open cutaway in a lid, or film-assisted mold (FAM) packaging in a quad-flat no-leads (QFN) or ball grid array (BGA) configuration. The sense and signal processing function integration is also possible in a single package using above technologies but are inefficient from size, cost and performance perspectives. Wafer-level chip-scale packaging (CSP) of image sensors have been developed. Packaging for both the sensor and the ASIC, whether together or separately, tends to occupy significant space. There is increasing emphasis on miniaturization of optical sensor assemblies across the electronics industry. Accordingly, there is a need for three-dimensional wafer-level integration of an optical sensor module with more compact packaging.